A systematic review of patient-reported outcome measures for idiopathic adhesive capsulitis - recommendations based on analyses of 16 existing questionnaires.

BACKGROUND

Patient reported outcome measures (PROMs) are essential to measure the patients' perspective in clinical studies. Like any measurement instrument, a PROM should be valid, reliable, and responsive. Adequate content validity relies on patient input, while construct validity can only be ensured by Modern Test Theory (MTT) models. Inadequate PROMs induce a significant risk of measurement errors. Currently, there is no thorough analysis of PROMs used in clinical research on idiopathic adhesive capsulitis (AC). The aim was to identify all PROMs used to evaluate AC, analyze their content and construct validity, and summarize the results in a recommendation on which PROM is the best for trials on AC.

METHODS

Musculoskeletal PROMs used to evaluate patients with AC were identified through PubMed searches in November 2024. Development and validity studies were identified for each PROM. Content validity was assessed based on existing guidelines emphasizing the involvement of patients in the development. Construct validity was assessed based on existing guidelines emphasizing the use of MTT models in the analysis. Both content and construct validity were rated from 1 to 5, and a concluding, aggregated assessment was made.

RESULTS

16 different PROMs, used up to 45 times, were identified. 79 articles on measurement properties were identified and analyzed. None of the PROMs had been developed specifically for patients with AC. Four PROMs were developed by the involvement of patients but with other conditions than AC. Five PROMs had been validated with an MTT model. However, all five possessed inadequate content validity. Hence, it was not possible to identify any PROM with adequate content and construct validity for patients with AC.

CONCLUSION

An adequate PROM for idiopathic AC does not exist and a new condition-specific questionnaire is needed. The existing PROMs should be used with significant reservations and results obtained by these PROMs should be interpreted with caution.